Prior gun sight alignment systems have depended on a worker's eye to judge the amount of sight adjustment required to make the bullet's impact coincide with the alignment of the front and rear sights of the gun. This process is generally called "zeroing in" the firearm. It has been the practice to initially adjust the sight to generally center each adjustable part vis-a-vis the barrel with each so positioned for elevation and for windage. Thereafter, the firearm is range tested by firing at a target and comparing holes in the target with the sight alignment as made with the tester's eye. The sights are then moved so that their alignment coincides with the bullet holes in the target. Thereafter when the gun is aimed and fired properly by the user, the bullets will strike where the sights indicate. The gun is then considered to be "zeroed in" and accurate shooting is now possible.
To aid in comparing target hits with the sight position relative to the barrel, telescopes have been suggested (U.S. Pat. No. 1,048,975). It has also been proposed to use lasers to align pipe conduit sections, pipe mill rollers, and machine turning tools (U.S. Pat. Nos. 3,631,601; 4,319,406; and 4,417,816).
Of relevance also is the prior suggestion of aligning sights on a gun by using two intersecting light beam sources; one beam through the bore of the barrel and one beam from a position above the barrel (U.S. Pat. No. 3,782,832).
No previous sight alignment system has used a laser to describe the actual line of sight on the target so as to simplify the process of aligning the path of the bullet with the sights.